Highway crossing signal control system



Sept. 29, 1953 o. w. ROST HIGHWAY caossme SIGNAL CONTROL SYSTEM Filed Feb. 17, 1950 INVENTOR.

H096 BY HIS ATTORNEY Patented Sept. 29, 1953 2,654,023 UNITED STATES PATENT OFFICE 2,654,023 HIGHWAY CROSSING SIGNAL "CONTROL SYSTEM Otto W. Rost, Chicago, Ill., rassignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Application February :17, 1950, SerialNo. 144,823 5 Claims. (01. 246-130,)

My invention relates to a highway crossing signal control system of the type adapted to provide protection for both directions of railroad traflic on a stretch of single track. More particularly my invention relates to a system of the 5 tures shall close its back contacts and which above described type which is arranged to pro shall .be latched .up. Although the signals will vide for proper operation should the track beoperate under these conditions whichever armacome shunted by a highway vehicle at thecrossture is closed, if the back contacts controlled by ing. the armature .of one approach section should A highway crossing signal control system auclose and .a train then enters the other approach tomatically initiates operation of a highway section, the signals will cease to Operate W11en crossing signal when a train approaches an inthe highway vehicle ceases to shunt the rails of tersection, and customarily discontinues suchopt e c o s ec a ill not p e vits the eration only when the train has cleared the train proceeds through the int rsec ion. crossing. On a stretch of single track intersected ,5 It is an Obj c f y inventiOIl provide a by a highway, protection of this type must be novel andiimproved'hi hw y cr ing signal onprovided for both directions of railroad traflic tl'ol system ofthetyp Which Will funcif trains are to move over the track in either dition to establish proper opera ion v n though rection. Where track circuits are employed, it a highway vehicle s unts the ls at t c s is usual in such cases to provide a crossinglsecg. tion which includes the intersection and two ap- Another object of my'invention is the provision proach sections located one on each side of the of .a novel and improved highw y ssi Si intersection adjoining the crossing section. Apr1851 o ol System f e p described Which paratus is then provided to initiate operation-of utilizes two interlocking relays d nc rp r t s the signals when a train travelling toward the means for maintaining the windings of each enintersection in either direction enters an apergized when the track section at the crossing is proach section, and to terminate operation when shunted by a vehicle moving across the tracks. the train vacates the crossingsection. Other important objects and characteristic 'One form of apparatus that has been proposed features of my invention will become apparent heretofore for accomplishing this result contemfrom the following description. plates the use of an interlocking relay to control In attaining the above mentioned and other thesignals, and a track circuit including a track objects of my invention, I provide two interlockrelay for each track section to control said ining relays anda track relay to control the operaterlocking relay. The interlocking relay ha two tion of 'the signals. One Winding of one interwindings each provided with an armature, and looking relayis connected across the rails of one an interlocking mechanism which on the release approach section and one winding of the other of either armature latches up the other armainterlocking relay connected across the rails ture to prevent it from closing its back contacts of the other approach section. The track relay if it should release before the first armature is is connectedacross the rails of t crossing picked up. The system is arranged to provide 0 tion. The other windings of the interlocking refor the deenergization of one winding of this inlays are jointly controlled over contacts of the terlocking relay when the track relay of one aptrack relay and'over contacts of the interlocking proach section is released, for the deenergization relays such that these windings ar maintained of the other winding when the track relay of the energized when the track circuit of the crossother approach section is released, and for the mg section is shunted by a vehicle moving across deenergization of both windings when the track the tracks, but are deenergized when the track rcrelay of the crossing section is released. The delay is released during normal operation by the sired protection is then obtained by controlling presence of aitrain in the crossing section. the signals over back contacts of the interlock- I shall describe one form of apparatus eming relay such that the signals are set into operabodying my invention, and shall then point out tion whenever one armature of the interlocking the novel features thereof in claims. relay has closed its back contacts. The accompanying drawing is .a diagrammatic Although apparatus of the above described view or one form of apparatus embodying my type will normally function in the desired maninvention. ner, any system so arranged incorporates an in- Referring now to the drawing, the reference herent difliculty in that proper operation of the characters to and l b designate the rails of a signals may be interfered with when the track given stretch of tlack ovei which traffic may circuit of the crossing section is shunted .by a move in either dllGCtIOIl and which a shown s crawler type tractor 'or similar vehicle moving intersected at'grade by ahighway H. A highway across the tracks. That is, when the track circo crossing signalsdesignated by the reference h 2 Cult of the crossing section :is shunted through the metallic treads and body of the vehicle both windingsof the interlocking relay arerdeenergized and it is indeterminateas .to which of the armaacter XS which may take any one of a number of suitable forms but which is represented as the flashing light type in the drawing, is located adjacent the intersection. The signal is controlled by an operating relay SR which may be of the flasher relay type illustrated in the drawing.

The flasher relay SR is characterized by the provision of two coils permanently connected in series, an armature mounted for attraction to either coil, and contacts operated between extreme right and left-hand positions depending upon the position of the armature. One contact 28 in its right-hand position establishes a shunt path around the right-hand coil of the relay, and in its left-hand position establishes a shunt on the left-hand coil. When the relay is deenergized the armature is biased to one of its extreme positions, for example, the left-hand position as shown in the drawing to assure a starting action so that when the relay is energized, the right-hand winding is first effective to create a flux which attracts the armature to its righthand position and contact 28 thereupon shunts the right-hand coil, whereupon the left-hand coil operates to attract the armature and the armature is alternately operated between its two extreme positions. The armature carries another contact 23 through which energy is supplied to the signal lamps. A relay of this type is shown, for example, in Letters Patent of the United States Reissue No. 17,252, dated April 2, 1929, to C. S. Snavely and W. B. Wells.

The track rails la and |b are divided by insulated joints 2 into an approach section AT located on one side of the crossing, a crossing section BT including the crossing and an approach section CT on the other side of the crossing. Each such section is provided with a track circuit including a track battery 3. The track circuits for sections AT and CT include windings 30 and 33, respectively, of interlocking relays WXR and EXR. The track circuit for section BT includes the winding of a track relay BTR.

Interlocking relays WXR and EXR are each characterized by the provision of a mechanical locking arrangement which for relay WXR is controlled by the armatures of windings 30 and 3| and for relay EXR is controlled by the armatures of windings 32 and 33. When both armatures of either relay are picked up, the release of one will latch up the other permitting its front contacts to open, but preventing its back contacts from closing if it should release before the first armature has picked up. Thus, taking relay WXR. as an example, if winding 30 is the first to be released, its front contact If! will open and its back contacts H and I2 will close, but the armature of winding 3| will be latched up so that when winding 3| subsequently becomes deenergized with winding 30 still released, its front contacts l3 and M will open but its back contacts l5 and It will be prevented from closing. A relay of this type is shown, for example, in Letters Patent of the United States No. 1,799,629, granted April 7, 1931, to W. K. Lockhart and T. J. 0-Meara.

As previously mentioned, winding 30 of relay WXR and winding 33 of relay EXR. are respectively connected in circuit with the rails of sections AT and CT and these two windings therefore are controlled by trafiic in the respective approach sections. The other winding 3| of relay WXR has a pick-up circuit governed by relay BTR which may be traced from terminal B of a suitable source of current, such as a battery not shown, through front contact ll of relay BTR.

.4 and winding 3| to the other terminal C of the same source of current, and it has a stick circuit extending from terminal B through front contact 22 of winding 32, front contact l4 of winding 3|, front contact IQ of winding 30 and winding 3| to terminal C. Winding 32 of interlocking relay EXR is similarly provided with a pick-up circuit controlled by front contact |8 of relay BTR and with a stick circuit which includes its own front contact 2|, a front contact 25 of winding 33 and a front contact I3 of winding 3|. Windings 3| and 32 are controlled by these circuits so that during normal operation, that is, when a train approaches the intersection through an approach section both windings will be released when a train enters the crossing section but will remain energized when a highway vehicle shunts the rails at the crossing and the sections are otherwise vacant.

Flasher relay SR is energized and set into operation over an obvious circuit which may be completed at back contact I! of winding 30, back contact iii of winding 3|, back contact is of relay BTR, back contact 23 of winding 32 or back contact 26 of winding 33. The signals are energized and set into operation over an obvious circuit which may be completed at back contact I2 of winding 30, back contact l6 of winding 3|, back contact 20 of relay BTR, back contact 23 of winding 32 or back contact 21 of winding 33.

The approach sections AT and CT located on opposite sides of the intersection each extend a distance equal to that which would be traversed in twenty seconds by a train operating at the highest authorized speed for the stretch. The crossing signals are set into operation, as will be made clear hereinafter, when a train approaching the intersection from either direction enters either section AT or section CT. As a result, the crossing signals are set into operation not less than 20 seconds before a train moving at the maximum authorized speed reaches the intersection. The crossing section which adjoins both approach sections merely spans the crossing and is relatively short with respect to the lengths of sections AT or CT.

The apparatus embodying my invention is illus-' trated in the drawing in the normal condition that obtains when the sections are unoccupied. In this condition of the apparatus both windings of each interlocking relay are energized and track relay BTR is picked up. As a result flasher relay SR. is deenergized and the signal is disconnected from the source of power.

When an eastbound train, that is a train operating from left to right as viewed in the drawing enters section AT, the shunting action of its wheels and axles deprives winding 30 of interlocking relay WXR of current. Front contact It) opens and back contacts H and I2 close in response. Back contact closes to complete the obvious energizing circuit for flasher relay SR previously mentioned and relay SR responds by alternately operating its contact 29 first to one position and then to another to cause the two lamps of signals XS to be energized alternately, one over a circuit which extends from terminal B over back contact l2 of winding 30 and contact 29 of flasher relay SR in its left-hand position through the filament of one lamp of signal XS to terminal C, and the other over a circuit which extends from terminal B over back contact H of winding 30 and contact 29 of flasher relay SR in its right-hand position through the filament of the other lamp of sig- Hal XSto trm'i-nal C. Front contact to of ing 30 prepares for the dee'nergizat'ion Wind'- ing 31 of interlocking relay WXR by opening the previously traced stick circuit which includes front contact 22 of winding 32, front contact M or winding 3| and front contact to of Winding an.

When the train enters section 13T it causes the release of track relay BTR. its back eontacfts f9 "and '20 close and its front contacts H and I 8 open and as a result energizing circuits are convpleted for the signals and the flasher relay over back contacts l9 and 10 which "circuits Thaintain the signals in operation as explained hereinafter when the train vacates "sectionrl'l and back contacts 11 and 12 of winding" -30 open. Front contact 'I 7 opens the previously tracedpickup circuit for winding 31 of interlocking relay WXR extending from terminal 13 over front contact 11 of relay BTR. through winding 31 to terminal C. Winding 3| then releases "and its front contacts l3 and I4 open. 'Its "back contacts I5 and I6 -are latched up by the interlocking mechanism of relay WXR. preventing them from closing.

The opening of front contact '14 "of winding 3| serves no 'immediatepurpose,"however, it"hol'ds open the stick circuit'previous'ly traced for winding 3| which extends over i'ront contact Ill when the train 'vacates section AT and contact 1''!) closes as eiml'aine'd hereinafter. Front contact I3 of winding 3| opens "the previously mentioned stick circuit for winding 32 of interlocking 'reia'y EXR extending from terminal is over front contact l3 of winding 3|, "front "contact 21o: winding '32 and 'front 'contact'25ofwinding 33 through winding 32 to terminal C. With front contact I 8 of'rel'ay BTR, openjth'e'previously traced'pickup circuit for winding 32 is now open and that winding releases opening its 'rront contacts f2! and22 and closing its back contacts 23 and 24. The opening of front contacts 2i and 22 performs no useful functionior eastbound traflic, but in the case of westbound tra'filc these contacts perform a function similar to -that of iron't contacts [3 and I4 of winding 3|. wh'en back contacts 23 and 24 close energizing circuits are completed over these contacts "for the flasher relay and the signaL'w-liich circuits maintain the signal in operation 'when the train -vacates section BT and back contacts 19 and 2:0 of relay BTR "open as explained "hereinafter. 7

When the train enters section CT winding 33 of interlocking relay .EXR -releases opening its front contact 25. Contact 25per'forms'no useful function in the case of eastbound tranlc, but it performs a function similar to that o'f'front contact in of winding '30 for westbound traffic. Back contacts 26 and 2'! do not close'whenwinding 33 releases -but are maintained in "a latched up :position instead by the interlocking mechanism of relay Y A I As the train vacates section .AT, winding '30 of interlocking relay WXR picks'up. "Front contact l0 olosesand back contacts H and [2 open. Although the energizing circuits 'for the signals and the flasher relay which extend over back contacts H and t2 are opened, alternate "circuit paths exist over back contacts l9 and of relay B'IZR and back contacts 23 "and 24 of winding 32, and the signalscontinue to operate. When front contact l0 closes 'it prepares the stick circuit for winding 3! of interlocking relay As the train vacates section BT relay 31 R picks up to close its front contacts 1 1 and i8 and open its back contacts 19 and 20 connected respectively in the obvious circuits for relay SR and signal XS. Although back contacts [9 and 20 open, back contacts '23 and 24 of winding 32 remain closed and the signal continues to operate. 'Whe'n front contact 17 of relay B'TR. closes *it completes the previously mentioned pickup circuit for winding 3"! of interlocking relay WXR which circuit extends from terminal'B'over front contact I"! of relay B'IR through winding 31 to terminal 0. Winding 3 picks up to close its front contacts 13 and i4 and to bring its *back contacts l5 and 16 from their latched up position to their energized position. When frontcontact 13 of relay BTR closes it completes the previously traced pick-up circuit 'for winding "32 of interlocking relay EXR which extends from terminal B over front contact l8 of relay B'IRthrough winding '32 to terminal '0. Winding '32 picks up to close its 'front contacts 2| and 22'and'to-open its back contacts 23 and 24. When back contacts 23 and 24 open they disconnect the flasher relay and the signal from the source of power and the signal ceases to operate. Front contact 2| closing prepares the stick circuit for winding '32 of interlocking relay EXR. Front contact 22, when it closes completes the previously traced stick circuit for winding 31 of interlocking relay 'WXR which includes front contact 22 of winding 32, front contact 14 of winding 3| and frontc'o'ntact 10 of winding 30.

When the train vacates section "CT winding 33 of interlocking relay EXR picks up. Its front contact 25 closes completing the stick circuit for winding -32 which circuit extends from terminalB'o'ver front contact 1-3 of winding 3 I, front contact 2| of winding "32 and from contact 25 of winding 33 through winding 32 to terminal C. When winding 33 picks up it brings back contacts 2'6 and 21 from their latched up position into their energized position. The apparatus has now resumed its normal condition, that is, the condition that it "normally obtains when each of the track sections is vacant.

The equipment operates in a substantially corresponding manner for westbound trafiic as it does for eastbound traflic, and a detailed description of its operation for westbound traffic is therefore believed unnecessary.

It follows from the foregoing description of the operation of the apparatus shown in the drawing that my invention is effective to maintain proper operation of the signal although a train entersan approach section during the time that a "vehicle moving across the tracks shunts the track circuit of the crossing section.

"If a crawler type tractor or similar vehicle shunts the track circuit at the crossing, track relayB'I R willrelease. Its front contacts l and will open and its back contacts l9 and 20 will close. When back contacts l9 and 2-0 close the signals are set into operation. Interlocking relays and are unaffected by the release of relay BTR for one winding of each is maintained energized over the track circuit with which it is associated, and the other windin is maintained energized over its own stick circuit. If an eastbound "train should enter section AT then, winding 30 of interlocking relay WXR, will release 'opening its lfront contact 10 and closing its back contacts H and 12 as in normal operation. When the highway vehicle ceases to shunt the'tr'a'ck circuit at "the crossing relay BTR. picks up closing its front contacts Hand t8 and open-- ing its back contacts 19 and 20. The signal is then operated over back contacts II and 12 of winding 33 and the normal mode of operation already described obtains as the train proceeds through the various track sections. Similarly, the equipment will operate in a substantially corresponding manner should a westbound train enter section CT while the track circuit at the crossing is shunted by a highway vehicle moving across the tracks.

Although I have illustrated and described only one form of highway crossing signal control systern embodying the features of my invention, it is to be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track intersected by a highway, a middle section including the crossing, a first and a second approach section located one on each side of the crossing, a signal for said intersection, a track relay, a track circuit including said track relay for said middle section, a first and a second interlocking relay, a first winding for said first interlocking relay controlled by the presence of a train on said first approach section, a second winding for said first interlocking relay jointly controlled by said track relay and by said second interlocking relay, a first winding for said second interlocking relay controlled by the presence of a train on said second approach section, a second winding for said second interlocking relay jointly controlled by said track relay and said first interlocking relay, and circuit means responsive to the operation of said interlocking relays and said track relay to control the operation of said signal.

2. In combination, a stretch of railway track intersected by a highway, a first, a second and a third section in said track stretch with said first and said third sections located on opposite sides of the crossing, and with said second section including the crossing, a signal for said intersection, a track circuit for said second section, a track relay included in said track circuit, an interlocking relay for said first section, an interlocking relay for said third section, a first winding for the interlocking relay of said first section controlled by the presence of a train in said first section, a first winding for the interlocking relay of said third section controlled by the presence of a train in said third section, a second winding for the interlocking relay of the first section, a second winding for the interlocking relay of said third section, circuit means jointly controlled by said track relay and by the first winding of each interlocking relay to control the second winding of that interlocking relay, and other circuit means responsive to the operation of said interlocking relays and said track relay to control the operation of said signal.

3. In combination, a stretch of railway track intersected by a highway, a first, a second and a third section in said track stretch with said first and said third sections located on opposite sides of the crossing, and with said second section extending over the crossing, a signal for said intersection, a track circuit for said second section, a track relay included in said track circuit, an interlocking relay for said first section, an interlocking relay for said third section, a first winding for the interlocking relay of the first section controlled by the presence of a train in said first section, a first winding for the interlocking relay of the third section controlled by the presence of a train in said third section, a second winding for the interlocking relay of the first section, a second winding for the interlocking relay of the third section, a control circuit for the second winding of the interlocking relay of the first section extending over a front contact of said track relay, a control circuit for the second winding of the interlocking relay of the third section extending over a front contact of said track relay, a stick circuit for the second winding of the interlocking relay of the first section extending over a front contact of the second winding of the interlocking relay of the third section, a front contact of the second winding of the interlocking relay of the first section and a front contact of the first winding of the interlocking relay of the first section; a stick circuit for the second winding of the interlocking relay of the third section extending over a front contact of the second winding of the interlocking relay of the first section, a front contact of the second winding of the interlocking relay of the third section and a front contact of the first winding of the interlocking relay of the third section; and circuit means responsive to the operation of said interlocking relay and said track relay to control the operation of said signal. 4. A highway crossing signal control system for a stretch of single track railway intersected at grade by a highway and divided into three successive adjoining track sections the middle one of which includes the intersection, said system including a highway crossing signal at said intersection, a track relay, a track circuit including said track relay for said middle section, interlocking relay means having first and second windings, means for controlling said first windings of said interlocking relay means by traific on the two outer track sections, a pickup circuit for each of said second windings each controlled by said track relay, a stick circuit for each of said second windings each controlled by the other second winding, and circuit means responsive to the operation of said interlocking relay means and said track relay to control the operation of said signal.

5. A highway crossing signal control system for a stretch of single track railway intersected at grade by a highway and divided into three successive adjoining track sections the middle one of which includes the intersection, said system including a highway crossing signal at said intersection, a track relay, a track circuit including said track relay for said middle section, two interlocking relays one for each outer track section and each having a first and a second winding, means for controlling the first winding of each interlocking relay by traflic in its respective outer track section, means for controlling said highway crossing signal by said track relay and said first windings of said interlocking relays, a pickup circuit for each said second winding controlled by a front contact of said track relay, and a stick circuit for each said second winding governed by the first winding of that interlocking relay and the second winding of the other interlocking relay.

. OTTO W. ROST.

References Cited in the file of this patent UNITED STATES PATENTS Number 

